drug interactions Flashcards
what are relative contrindications
caution is needed using 2 medicines or procedures together
what are absolute contraindications
- the substance can cause a life threatening situation
- don’t give together, risks outweigh the benefit
what are type A ADRs
from the pharmacological effect of the drug
what are type b ADRs
unpredictable and non dose dependent
which drugs usually provoke an allergic reaction
- antibiotics
- NSAIDS
- cancer chemotherapy
- monoclonal antibodies
what are the characteristics of anaphylaxis
- vasodilation and increased vascular permeability
- hypotension
- tachycardia
- dyspnoea
- urticaria
- reduced level of consciousness
what are type C ADRS
- continuing reactions
- persist for a long time
what are type D ADRs
- delayed reaction
- apparent after medication usage
what are type E ADRs
- end of use reactions
- withdrawal of medication
what is a precipitant in drug interactions
the drug that is causing the reaction
what is an object
the drug that is affected by the reaction
what are pharmaceutical drug interactions
- interactions prior to taking the drug
- the combination of ingredients alters the physical and chemical properties making it unstable
what causes chemical pharmaceutical drug interactions
- oxidation-reduction
- exchange
- hydrolysis
- substitution
- decomposition
- neutralization
what influences GI absorption
- bind drugs
- increase GI motility
- decrease GI motility
- increased gastric pH
how is subcutaneous absorption slowed
- giving vasoconstrictors
- cardiac decrepssants
what drug interaction alter distribution and binding
- competition for plasma protein binding
- displacement from tissue binding sites
- alterations in local tissue barriers
how can drug metabolism be increased
through other agents such as P450 enzymes eg ethanol, rifampin
how can drug metabolism be decreased
through inhibition of drug metabolizing enzymes eg amiodarone, disulfiram
what is the effect of drugs reducing hepatic blood lfow
reduces clearance of other drugs metabolised in the liver
how can drugs affect renal excretion
- reduced renal blood flow
- inhibit specific renal transport mechanisms
- alter urine Ph
how does a change in urine pH affect renal excretion
changes to renal tubular reabsorption of weak acids or weak bases
how do drug interactions cause additive effects
- can act on same receptor and produce the same effect
- excessive affects can be caused
what are supra-additive interactions
result of interaction is greater than the sum of the drugs used alone
what is potentiation
when the drugs effect is increased by another agent that has no effect
